SOLUTION: If x = 4y + 3 and y = –2x – 3, what is the value of xy? A) –1 B) 0 C) 1 D) 3

Algebra ->  Equations -> SOLUTION: If x = 4y + 3 and y = –2x – 3, what is the value of xy? A) –1 B) 0 C) 1 D) 3      Log On


   

Question 998751: If x = 4y + 3 and y = –2x – 3, what is the value of
xy?
A) –1
B) 0
C) 1
D) 3
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Use the equations to solve for x and y. First we'll solve for x after doing a substitution
x = 4y+3
x = 4(-2x-3)+3
x = 4(-2x)+4(-3)+3
x = -8x-12+3
x = -8x-9
x+8x = -9
9x = -9
x = -9/9
x = -1

Now find y
y = -2x-3
y = -2(-1)-3
y = 2-3
y = -1

Finally, multiply the values
x*y = (-1)*(-1) = 1


Final Answer: C) 1